Well completion apparatus



25, 1964 H. GREKEL ETAL WELL COMPLETION APPARATUS 2 Sheets-Sheet 1 Filed Nov. 2. 1961 HOWARD GREKEL GEORGE C HOWARD KAROL L. HUJSAK INVENTORS. 2 0M86 ATTORNEY.

25, 1964 H. GREKEL ETAL WELL COMPLETION APPARATUS 2 Sheets-Sheet 2 Filed NOV- 2. 1961 HowARD GREKEL GEORGE C. HOWARD KAROL L. HUJSAK INVENTORS. BYM. )W 7' ATTORNEY.

United States Patent Ofiice 3,145,778 Patented Aug. 25, 1964 3,145,778 WELL COMPLETION APPARATUS Howard Grekel, George C. Howard, and Karol L. Hujsak, Tulsa, Okla, assignors to Pan American Petroleum Corporation, Tulsa, Okla, a corporation of Delaware Filed Nov. 2, 1961, Ser. No. 149,670 4 Claims. (Cl. 166-157) The present invention relates to an improved apparatus for completing wells. More particularly, it is concerned with an improved liner design used in conjunction with a gravel-packed zone in a producing well wherein sand control is a problem. The device itself includes a tubing section and a perforated liner surrounding and slidably mounted on the tubing section. Between the liner and the tubing is a seal aflixed to the top portion of the liner. Means is provided in the tubing by which a stream of cleaning fluid can be jetted therefrom, through the liner and into the gravel pack when the latter becomes plugged or flow through the pack is substantially reduced. Since the liner is slidably mounted on the tubing, this jetting action to recondition the gravel pack may be performed throughout the height of the pack, thus afiording a convenient and eifective means of restoring the permeability of the gravel screen.

While the discussion which follows is directed, primarily, to sand control problems connected with the production of oil from unconsolidated tar sands by underground combustion methods, it should be clearly understood that our invention may be used with equal effectiveness in wells where oil is produced by conventional means, but where sand is produced in objectionable amounts along with the oil.

The problem of sand control in producing oil from certain formations is an old one and numerous methods have been devised to combat it. One of the more effective schemes used today involves packing the sand-producing zone with a small, i.e., 20 to +40 mesh US. Standard sieve gravel and either producing through a solid section of such gravel or producing through a vertical layer of the gravel supported against the sides of the well bore by means of a suitable perforated metal liner or screen. The oil coming into the liner is relatively sand-free and can be produced through the tubing without damage to the equipment either below or at the surface. These gravel packs oftentimes, however, become plugged and have to be replaced with clean material.

Formations which give rise to sand control problems also present other operating difliculties. For example, where unconsolidated tar sands are being subjected to combustion as a means for recovering the tar therefrom, the casing must be capable of withstanding the pressures exerted on it by the settling or caving-in of depleted sand in the burned area. Also, the casing should be able to resist corrosion caused by air at high temperatures, as well as the effect of thermal shock caused by circulation of cooling water during the wells producing life.

The apparatus of our invention may be more fully explained by reference to the accompanying drawings, in which:

FIGURE 1 is a vertical sectional view showing the portion of the tubing immediately after disconnection from the base of the screen and the position of the jets in the tubing with respect to the liner openings.

FIGURE 2 is also a vertical sectional view illustrating the apparatus installed in a well with the tubing partially withdrawn from the liner and in position to clean the gravel pack from the top down.

In FIGURE 1, a liner 2 with perforations 4 surrounds well tubing 6. For use in high-temperature, i.e., 400- 600 F. wells, the liner and portions of tubing exposed to such conditions should be constructed of a temperatureand corrosion-resistant material such as, for example Inconel, Incoloy, or 25-30 stainless steel. At the top of the liner a ring seal 8 is affixed, providing a substantially liquid-tight seal between the tubing and liner. This seal may be constructed from a number of materials such as, for example, brass, an iron ring wrapped with graphiteimpregnated asbestos rope, a silicone rubber, etc.

Tubing 6 may be secured to the liner, if desired, by engagement of threaded end 10 with threaded socket 12 at the base of the liner. Below sealing ring 3, and within liner 2, are attached two opposed, cup-type packers 15 on either sideabove and below-of ports 14 in tubing 6. These packers, in the case of wells in which the temperature seldom exceeds about 400 F., may be constructed of any of several hydrocarbon and temperatureresistant rubbers such as, for example, neoprene or silicone rubber. Where higher temperatures are encountered, metal petal baskets may be employed. To form a better seal around the edge of the basket, a rope of woven asbestos fibers may be attached to said edge. In some cases the entire elements themselves may be made up of woven asbestos fabric. In other instances these elements may be in the form of reinforced ceramic discs, etc. The principal function of packers 16, of course, is to confine fluid injected from tubing 6 via ports 14 so that the bulk of such fluid is directed toward a particular level of liner perforations 4. Thus, any known structure capable of performing this function is to be considered the equivalent of packers 16. These packers have a strong, protruding shoulder portion 2$ which, when tubing 6 is lifted upwardly with respect to liner 2, engages ring seal 8. Further lifting of tubing 6 results in dislodging the liner, and by this means may either be removed from the well or allowed to settle back into its original position after breaking free from objectionable materials tending to impede flow into the well bore. The upper lip of packer 16 should fit loosely enough within the liner when collapsed to permit easy flow of oil or tar into the tubing ports. During the back-washing operation, the pressure exerted against the upper and lower lip of packer 16 causes these elements to seal against the liner. If a metal petal basket is used, clearance between the liner and the individual petals can be provided during oil-producing operations.

While the upper lip or element has its principal advantage when used in combination with a lower element, it will be apparent that some advantages are obtained by the use of the upper element alone to limit the washing action to the zone below said element and thus avoid bypassing of washing liquid through the top portion of the liner which has already been cleaned.

The lower end of tubing 6 is provided with a valve seat 18 into which an upwardly-displaceable check valve 29, having a fishing head 22, may be placed. At the base of threaded socket 12 is a downward-displaceable springactuated check valve 24 which normally engages valve seat 26.

In FIGURE 2, the apparatus is installed in a well having casing 30 with perforations 32 to permit the entry of fluids from formation 33 into the well. Behind the casing is a fire-resistant cement 34 which may be any of several materials known to be suitable for this purpose such as, for example, alumina cement containing silica flour or ground fire brick. Graded sand (gravel) 36 is packed between liner 2 and casing 30. Tubing 6 is equipped with a back-off joint 38 to permit workover operations or removal of the production tubing. The use of cement and perforated casing is preferred, in most cases, to prevent collapse of the formation around the liner. A second liner, smaller than the casing but larger than liner 2, can be hung in the bottom of the casing, extended through the producing interval, and cemented in place, if desired, instead of extending the casing through the producing formation. The openings in this outer liner should be larger than those in liner 2. This is to delay and possibly avoid plugging of the openings in the outermost liner. If plugging of these larger openings occurs, liner 2 can be washed free and removed from the well. The outer perforated liner or screen can then be cleaned by use of liquid jets, solvents, or the like, in accordance with procedures well known to the art.

In using the novel device of our invention, gravel is placed into the well opposite the particular producing zone from which it is desired to control the flow of sand. After the gravel has been placed in accordance with methods now well known to the art, liner 2, which is hung on tubing 6 by means of threaded section 12 being engaged with the threads in the bottom of tubing 6, is lowered into the well until it reaches the gravel pack. At that time, or slightly before, if desired, water or other suitable liquid is forced down the tubing 6 from which check valve 26 has been removed. When fluid reaches the bottom of tubing 6, which is secured to liner 2 by means of threaded socket 12, the tubing check valve 24 is forced open allowing fluid to temporarily wash away the gravel so that the liner may be lowered farther. This operation is continued until the device rests opposite the producing zone. Gravel settles around the liner in the form of a moderately-packed layer 36, thus serving as a screen or filter for sand-laden formation fluids.

When gravel pack 36 becomes plugged, or its permeability is noticeably decreased, water or other suitable cleaning fluid is forced down through the tubing and into the liner. In this way the liner can be backwashed and the gravel floated and thoroughly cleaned from plugging material such as clay, fine sand, etc., which are forced up the annulus and removed from the well. When backflow of the cleaning fluid is stopped, the cleaned gravel settles back around the liner and production is resumed.

In some instances, however, the gravel cannot always be cleaned effectively in this way, and resort must be had to other measures. Thus, where the gravel is plugged so tightly that vertical flow through valve seat 26 and upwardly through the gravel pack cannot be readily accomplished, retrievable check valve 20 is lowered or dropped into the tubing where it comes to rest in valve seat 18. Tubing 6 is then disconnected from the base of liner 2 at threaded socket 12 and raised until shoulders 28 strike sealing ring 8. With valve 20 in place, water is forced down through the tubing and jetted out through ports 14, serving to clean liner 2. Also, this water under pressure is forced through perforations 4, resulting in washing occluded material from gravel pack 36. Packers 16 tend to limit or confine the flow of water through a single level of perforations 4 near the upper part of pack 36. By loosening the gravel at the top of liner 2 in this way, and then lowering tubing 6 a short distance at a time, the remainder of the gravel can be similarly loosened and freed of objectionable matter.

It will be apparent to those skilled in the art that applications of our invention other than those enumerated above may be employed. For example, in many cases the liner and tubing can be placed in an uncased well. By use of the slidable connection between the liner and the tubing in accordance with the procedure mentioned above, the liner can be washed free from sand which fills in around it.

We claim:

1. Apparatus for use in a well comprising tubing,

a perforated liner surrounding said slidably mounted on said tubing which opens into said liner, means for opening and closing the base of said tubing,

sealing means at the upper end of said liner and between said tubing and said liner,

means on said tubing for engaging said sealing means when said tubing is moved upwardly with respect to said liner,

means defining passageways through the side of said tubing communicating directly with the interior of said liner,

means mounted on said tubing for confining the flow of a fluid from said passageways to a given level of perforations in said liner,

means for affixing the lower end of said tubing to the bottom of said liner, and means at the bottom of said liner for the control of fluid flow therefrom when said tubing is secured to the bottom of said liner.

2. Apparatus for use in a well comprising tubing,

a perforated liner surrounding and slidably mounted on said tubing which opens into said liner, means for opening and closing the base of said tubing,

sealing means at the upper end of said liner and between said tubing and said liner,

means on said tubing for engaging said sealing means when said tubing is moved upwardly with respect to said liner,

means defining passageways through the side of said tubing communicating directly with the interior of said liner,

means for detachably mounting said tubing to the bottom of said liner,

means mounted on said tubing for confining the flow of a fluid from said passageways to a given level of perforations in said liner,

and means at the bottom of said liner for the control of fluid flow therefrom when said tubing is mounted to the bottom of said liner.

3. Apparatus for use in a well comprising tubing,

a perforated liner surrounding and slidably mounted on said tubing which opens into said liner, means for opening and closing the base of said tubing,

sealing means at the upper end of said liner and between said tubing and said liner,

means on said tubing for engaging said sealing means when said tubing is moved upwardly with respect to said liner,

means defining passageways through the side of said tubing communicating directly with the interior of said liner,

means mounted on said tubing for confining the flow of a fluid from said passageways to a given level of perforations in said liner,

means at the bottom of said liner for the control of fluid flow therefrom,

and means at the bottom of said liner for the control of fluid flow therefrom when said tubing is mounted to the bottom of said liner.

4. Apparatus for use in a well comprising tubing, a perforated liner surrounding and slidably mounted on said tubing which opens into said liner, sealing means at the upper end of said liner and between said tubing and said liner, means on said tubing for engaging said sealing means when said tubing is moved upwardly with respect to said liner, means defining openings in said tubing placing the latter in fluid communication with said 5 (-5 liner, means mounted on said tubing for confining the said liner for the control of fluid flow therefrom when flow of a fluid from said openings to a given level of said tubing is secured to the bottom of said liner. perforations in said liner, means for detachably mount- References Cited in the file of this patent ing said tubing to the bottom of said liner, a removable check valve in said tubing adjacent said means for detach- 5 UNITED STATES PATENTS ably mounting said tubing to the bottom of said liner, 2,092,042 Armentrout et a1 Sept. 7, 1937 whereby the flow of fluid from said tubing can be con- 2174795 Layne 1939 2,217,215 Coberly Oct. 8, 1940 trolled, and pressure responsive means at the bottom of 2,442,544 Johnson June 1 1948 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 145,778 August 25, 1964 Howard Grekel et a1,

It is hereby certified that error appears in. the above numbered patent" requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 8, for "said" read and lines 62 and 63, strike out "means at the bottom of said liner for the control of fluid flow therefromfl'.

Signed and sealed this 5th day of January 1965.

SEAL) Attest:

ERNEST. W-. SWI'DER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. APPARATUS FOR USE IN A WELL COMPRISING TUBING, A PERFORATED LINER SURROUNDING SAID SLIDABLY MOUNTED ON SAID TUBING WHICH OPENS INTO SAID LINER, MEANS FOR OPENING AND CLOSING THE BASE OF SAID TUBING, SEALING MEANS AT THE UPPER END OF SAID LINER AND BETWEEN SAID TUBING AND SAID LINER, MEANS ON SAID TUBING FOR ENGAGING SAID SEALING MEANS WHEN SAID TUBING IS MOVED UPWARDLY WITH RESPECT TO SAID LINER, MEANS DEFINING PASSAGEWAYS THROUGH THE SIDE OF SAID TUBING COMMUNICATING DIRECTLY WITH THE INTERIOR OF SAID LINER, MEANS MOUNTED ON SAID TUBING FOR CONFINING THE FLOW OF A FLUID FROM SAID PASSAGEWAYS TO A GIVEN LEVEL OF PERFORATIONS IN SAID LINER, MEANS FOR AFFIXING THE LOWER END OF SAID TUBING TO THE BOTTOM OF SAID LINER, AND MEANS AT THE BOTTOM OF SAID LINER FOR THE CONTROL OF FLUID FLOW THEREFROM WHEN SAID TUBING IS SECURED TO THE BOTTOM OF SAID LINER. 